Question

For a school science experiment, Sam took three jars of equal sizes and filled them with equal amounts of nutrient-rich soil. From a bag of mustard seeds, he sowed 10 seeds in Jar A, 20 seeds in Jar B, and 40 seeds in Jar C. All three jars were given the same amount of water and exposed to the same amount of sunlight daily.

The growth of the mustard plants was monitored for three weeks, and the following measurements show the average height of the seedlings and were recorded at the end of each week.

JAR A JAR B JAR C
Week 1 4 cm 3.2 cm 3 cm
Week 2 8.5 cm 6.6 cm 5.8 cm
Week 3 14 cm 10.2 cm 8.6 cm

What can Sam conclude from the recorded data?
A.
The growth rate of mustard plants is controlled completely by the seeds' genes.
B.
The growth rate of mustard plants is affected by the number of seeds planted in a particular area.
C.
The growth rate of mustard plants does not depend on the environment in which the seeds are grown.
D.
The growth rate of mustard plants remains constant as the plants grow from seeds.

Answer 1

Answer: B.

Explanation: All jars had the same soil, water and sunlight, so the main difference was seed density. Jar A (10 seeds) produced the tallest seedlings on average, Jar B (20) intermediate, Jar C (40) the shortest. This pattern indicates crowding/competition (for nutrients, water, light, space) reduces growth, so growth rate is affected by the number of seeds planted per area. Options A, C and D are not supported by the data.